3D images can perform more sophisticated representation than 2D images, and therefore, combined with advances in image display technology in recent years, have drawn increasing attention. A 3D image is implemented by using recognition of a space to be three-dimensional due to a parallax between left and right eyes. More specifically, the 3D image is implemented by an image display device as shown in FIG. 50. A 3D image display unit receives an input image for a left eye (left-eye parallax image) and an input image for a right eye (right-eye parallax image) to adjust these images to be recognized separately between the right and left eyes of the observer, thereby implementing 3D representation (three-dimensional representation). The left-eye parallax image and the right-eye parallax image are represented by signals generated in view of a parallax between the right and left eyes.
Patent Document 1 discloses a technology of detecting a region of a stereoscopic video an observer is estimated to gaze at when observing the stereoscopic video, applying a lowpass filtering process to a signal representing a region having a parallax amount different from that of this detected region, thereby causing the observer to perceive the region other than the region estimated to be gazed at by the observer in a blurred state.
Patent Document 2 discloses a technology of generating a pseudo three-dimensional video signal. When an optical flow in a two-dimensional video signal is larger than a predetermined value, a time difference corresponding to the optical flow is added. A parallax is thereby generated. The two-dimensional video signal is converted to a left-eye video signal and a right-eye video signal in a pseudo manner. The pseudo three-dimensional video signal is generated based on the left-eye video signal and the right-eye video signal.
Patent Document 3 discloses a technology of adding identification information indicating a stereoscopic image to stereoscopic image data. In this technology, when an observer observes the stereoscopic image by a device that can perform stereoscopic display, the observer is made to perceive that the image he is observing is the stereoscopic image. On the other hand, when the observer observes the stereoscopic image by a device that can perform stereoscopic display, the identification information added to the stereoscopic image is disposed at a position that does not impede the stereoscopic display of the stereoscopic image.
Patent Document 4 discloses a technology of displaying a mixture of 2D and 3D images and performing stereoscopic display, thereby reducing an amount of data and power consumption. An image display device described in Patent Document 4 is constituted from a parallax image generation unit and a 3D image display unit. The parallax image generation unit receives a two-dimensional image, a region of interest image, and region of interest shape information or a depth image signal. The parallax image generation unit converts a region corresponding to the region of interest of the two-dimensional image to images taken from two different viewpoints. The parallax image generation unit generates a left-eye parallax image and a right-eye parallax image, for output. The 3D image display unit rearranges the generated left-eye parallax image and the generated right-eye parallax image to perform display of a mixture of the 2D and 3D images.
The received two-dimensional image is represented by a signal indicating an image viewed from one of the right and left viewpoints, for 3D display. The region of interest image is an image representing a region of interest in the two-dimensional image. The region of interest means a region of the entire two-dimensional image to be stereoscopically shown. The region of interest shape information includes information such as the position and the shape of the region of interest in the two-dimensional image. The depth image signal is a signal indicating a distance between the viewpoint and an object within the two-dimensional image, in a three-dimensional space.
The parallax image generation unit performs geometric transforms such as affine transform and transmitting transform and filtering in a frequency domain on a signal indicating the region of interest to give a parallax to each pixel in the region of interest image. An image having a mixture of the 2D and 3D images is thereby generated. That is, the generated image of a region other than the region of interest that is represented by the left-eye parallax image and the right-eye parallax image is the same as the two-dimensional image of the region other than the region of interest. The left-eye parallax image and the right-eye parallax image are images having a parallax with respect to the region of interest alone, and are the same with respect to the region other than the region of interest.    [Patent Document 1] JP Patent Kokai Publication No. JP-A-11-155154    [Patent Document 2] JP Patent Kokai Publication No. JP-A-7-281644    [Patent Document 3] JP Patent Kokai Publication No. JP-P-2007-036528A    [Patent Document 4] International Publication No. WO2010/116614